Damage to windshields caused by debris or other impacts has long been a problem. Many patents have issued and a substantial business thrives respecting the repair of such damage. For a long time it was believed that long cracks, that is cracks over six inches in length could not be repaired. However, shorter cracks referred to as stone damage were repairable. Later through significant developments in the field it became possible to repair long cracks. Patents which relate to the repair of long cracks in windshields are U.S. Pat. No. 5,116,441, U.S. Pat. No. 5,425,827, U.S. Pat. No. 5,429,692, U.S. patent application Ser. No. 08/436,155, U.S. patent application Ser. No. 08/436,591 and U.S. patent application Ser. No. 08/459,039.
Also, there is a thriving business in the replacement of cracked windshields which either cannot be repaired or which are believed to be unrepairable. In fact replacement is vastly more common than repair.
Despite these thriving businesses damage to windshields present costs to the consumer because of the cost of the repair or replacement. When insurance covers the damage then there is an insurance company loss which is passed on to consumers through their premiums. Also tons of unrecycled waste are created year after year.
Impacts which cause damage near the glass edge nearly always result in an edge crack, that is a crack running through the impact point to the edge of the glass. These cracks are also nearly always long cracks, that is over 6 inches in length. By contrast impacts in the middle area of the windshield quite often result only in the limited damage known as chips or stone damage, that is a bullseye, a star break or a combination and absent any long crack. Thus the problem of windshield damage in the peripheral area is considerably greater than in the middle. Long cracks, especially edge cracks, demand attention soon after cracking and most end up being replaced.
Windshields are installed with a rubber or plastic and in some cases metal, molding. Presently, most moldings are 1-2 centimeters wide, about 50% of the molding width extending over the glass. The maximum known molding width covers 2 cm of the windshield glass.